5 EGL diamond comparisons - which one should I choose?

[Gypsy]

Old post requote

"1.4 crt round (7.2mm in dia): 40.71 sq. mm
1.5 crt princess (6.4x6.4): 40.96 sq. mm"

This may help put sizing into perspective and the above assumes proper cuts and depths for both shapes

Those numbers aren't entirely accurate. The round is 7mm (not 7.2) and the princess is 6mm.

Here are the two stones.
http://www.jamesallen.com/loose-diamonds/princess-cut/1.42-carat-j-color-vs1-clarity-sku-364034
http://www.jamesallen.com/loose-diamonds/round-cut/1.20-carat-j-color-si1-clarity-excellent-cut-sku-361102

 

[Sunstorm]

I agree with Gypsy, square shapes princess for one faces up way smaller than rounds like noticeably smaller in my opinion. Ovals and pears can face up much larger than their carat weight would suggest but yes both cuts, though in my opinion really gorgeous with pear being my favorite shape, are hard to shop for and get quality for someone who may not know diamonds. Yes, RB sounds challening enough here, OP please read the info suggested carefully because of light leakage in a poorly cut stone if you choose carat weight over cut your higher carat stone will look much smaller than a truly ideal cut in the carat range Gypsy suggested not to mention the vast difference you will get when you own a stone with superb cut, the visual difference cannot be emphasized enough. Always sacrifice carat for cut, balance the other factors so you get the most for your money but never compromise on the cut and in the US I would only accept stones with GIA or AGS certs. In Europe IGI and HRD can be fine, my IGI Antwerp Fs grade as Es. But in the US stick to those two mentioned. In case of fancy colors I would probably accept only GIA anywhere and perhaps Gübelin but you are not shopping for fancy colors.

 

[sturgeon123456]

I agree with Gypsy, square shapes princess for one faces up way smaller than rounds like noticeably smaller in my opinion. Ovals and pears can face up much larger than their carat weight would suggest but yes both cuts, though in my opinion really gorgeous with pear being my favorite shape, are hard to shop for and get quality for someone who may not know diamonds. Yes, RB sounds challening enough here, OP please read the info suggested carefully because of light leakage in a poorly cut stone if you choose carat weight over cut your higher carat stone will look much smaller than a truly ideal cut in the carat range Gypsy suggested not to mention the vast difference you will get when you own a stone with superb cut, the visual difference cannot be emphasized enough. Always sacrifice carat for cut, balance the other factors so you get the most for your money but never compromise on the cut and in the US I would only accept stones with GIA or AGS certs. In Europe IGI and HRD can be fine, my IGI Antwerp Fs grade as Es. But in the US stick to those two mentioned. In case of fancy colors I would probably accept only GIA anywhere and perhaps Gübelin but you are not shopping for fancy colors.

Its an illusion because its round and saying way bigger is an exaggeration as the percentages are so small.

http://www.jamesallen.com/loose-diamonds/princess-cut/1.39-carat-j-color-si1-clarity-sku-358796

39.81 mm squared actual surface area

A 7mm round has a surface area of 38.47

Take the diagonal measurement and the princess will always be larger than the round if cut properly.

A round pavilion eats up a lot of carat weight compared to a square one as well so although depths are lower on rounds the pavilion has more weight.

This misconception that rounds face up way larger is just bogus. Maybe if your eyes can sense a 2-3% tolerance in such a small stone, and your eyes cant figure out that the princess is more dense due to the shape, on top of that the diagonal plane measurement is larger on a princess etc etc..... I have seen hundreds if not thousands of princess and rounds and unless the depth is outrageous and the crown angles are really high I do not see rounds as facing up "way bigger" The illusion is only slightly larger.

Not to mention that you can buy a bigger stone for the money when purchasing a fancy shape so if you go strictly dollar to dollar you will get a stone that is larger, faces up larger and has a larger surface area.

 

[adele_h]

No. The appraisal doesn't help. DO. NOT. BUY. AN. EGL. STONE.

Okay?

Also since it's obvious that your research to date hasn't really educated you very well, here's what you need to know.

The entire purpose of faceting a diamond is to reflect light.
How well or how poorly a diamond does this determines how beautiful it is.
How well a diamond performs is determined by the angles and cutting. This is why we say cut is king.
No other factor: not color, not clarity has as much of an impact on the appearance of a diamond as its cut. An ideal H will out white a poorly cut F. And GIA Ex is not enough. And you must stick to GIA and AGS only. EGL is a bad option: [URL='https://www.pricescope.com/community/threads/egl-certification-are-any-of-them-ok.142863/']https://www.pricescope.com/community/threads/egl-certification-are-any-of-them-ok.142863/[/URL]
So how to we ensure that we have the right angles and cutting to get the light performance we want?
https://www.pricescope.com/wiki/diamonds/diamond-cut
Well one method is to start with a GIA Ex, and then apply the HCA to it. YOU DO NOT USE HCA for AGS0 stones.
https://www.pricescope.com/wiki/diamonds/holloway-cut-advisor
The HCA is a rejection tool. Not a selection tool. It uses 4 data points to make a rudimentary call on how the diamond may perform.
If the diamond passes then you know that you are in the right zone in terms of angles for light performance. Under 2 is a pass. Under 2.5-2.1 is a maybe. 2.6 and over is a no. No score 2 and under is better than any other.
Is that enough? Not really.
So what you need is a way to check actual light performance of your actual stone.
That's what an idealscope image does. https://www.pricescope.com/wiki/diamonds/firescope-idealscope
It shows you how and wear your diamond is reflecting light, how well it is going at it, and where you are losing light return. That is why you won't see us recommending Blue Nile, as they do not provide idealscope images for their diamonds. BGD, James Allen, GOG, HPD, ERD and WF do.

The Idealscope is the 'selection tool'. Not the HCA.
So yes, with a GIA stone you need the idealscope images. Or you can buy an idealscope yourself and take it in to the jeweler you are working with to check the stones yourself. Or if you have a good return policy (full refund minimum 7 days) then you can buy the idealscope, buy the stone, and do it at home.


Now if you want to skip all that... stick to AGS0 stones and then all you have to do is pick color and clarity and you know you have a great performing diamond. Because AGS has already done the checking for you. That's why they trade at a premium.

Gypsy, may I ask why you don't use the HCA for AGS 0 diamonds?
Many thanks!

 

[SirGuy]

The HCA uses just a few numbers to give a broad idea of how a stone may perform. That's part of the reason it's a rejection tool; it's easier to kick out ones that would likely be outside acceptable margins than to select ones that are better than each other within a threshold.

AGS has what is generally regarded as the most strict lab on cut right now. Unlike GIA's proportion-based grading, AGS uses sophisticated 3D ray-tracing equipment to map the facets' light return, in what we call light performance.

In other words, AGS has done the work for you. The HCA is a far rougher estimate than the report generated by AGS using their data.

 

[Gypsy]

HCA uses 4 data points to make a rudimentary call on how a diamond may perform. AGS evaluates the actual stone for performance. AGS trumps HCA each time.